2000 shuts off but starts right back up idles/runs super smooth

[bear91]

My new to me 7.3 powerstroke excursion has shut off twice while idling and once while slowly reversing in a parking spot.
Tack moves when cranking, no codes on dash, idles and runs really smoothly.

I bought a cps from riffraff but from my research the CPS makes it run bad?

Oh yesterday it didn't wanna start (cranks and tach moves) but waited 4 hours went out there after temps dropped drastically and it started right up idles smooth.

One battery is testing bad but cranks fast and alternator looks new. I will be replacing both batteries soon.

Truck has a 6 position chip, installed by a previous owner. Could that be causing these issues?

If it makes a difference the theft light flashes consistently

 

[Kevin 007]

Start with the CPS.
Also possibly the ICP,
Check the tin nut on the IPR
Check the square harness plug on the drivers side of the engine, make sure it's not rubbing on the valve cover.
Check all your grounds, then check them again.

 

[Black dawg]

Like already said, start with the cps, and check that dang nut is still on the ipr.....seen that one many times now.

Also, make sure whatever is plugged into the ecm is in fully, and the connections are clean.

 

[Rdnck84_03]

If you have a battery that tests bad I would start with replacing both batteries. You have to have atleast 10-10.5 volts while cranking or the pcm wont signal for the injectors to fire (doesnt matter how fast the engine spins).

These trucks are notorious for not starting even when both batteries test good. I usually average about 2 years on a pair of group 65 in my 3 powerstrokes, usually get about 3 more years in a gas vehicle or tractor after they won't start a powerstroke.

James